The present invention relates generally to an improved multi-function actuator having a motor that is operatively arranged to initially displace a first mechanism (e.g., a first crank controlling the displacement of a thrust vector control vane) through a first displacement range, having a second mechanism (e.g., an aerodynamic steering fin) that is capable of spring-driven uni-directional displacement from a first (e.g., stowed) position to a second (e.g., deployed) position when the first mechanism is moved beyond such first displacement range; and having a clutch operated by the release of the spring to selectively disconnect the motor from the first mechanism and to selectively connect it to a third mechanism (e.g., a second crank controlling the angle-of-attack of the deployed fin) such that the motor may be operated to selectively control the third mechanism.
In certain applications, a missile is initially controlled by means of a thrust vector control vane positioned in the rocket jet stream. After launch, it may be desirable to deploy steering fins that have been stowed within the missile body, and to thereafter control the angle-of-attack of these fins to control the flight of the missile.
One might intuitively think that a first motor would be used to control movement of the thrust vector control vane, a second motor would be used to control the deployment of the fins, and a third motor would be used to control the angle-of-attack of the deployed fins. However, use of multiple actuators to control these three functions would add unnecessary weight and complexity to the missile, and would reduce its potential payload.
U.S. Pat. No. 4,709,877 discloses a mechanism having one motor for deploying a fin from a stowed position to a deployed position, and then for controlling the angle-of-attack of the deployed fin. According to this patent, the motor rotates a gear mounted on an initially-fixed support member to first perform the deployment function. Completion of this initial motion releases a spring-loaded pin to lock the fin in its deployed position, and also releases the support member so that further rotation of the gear may be used to control the angle-of-attack of the deployed fin.
It would be generally desirable to provide an improved multi-function actuator having a single motor that is capable of: (1) initially controlling a thrust vector control vane of a rocket motor, (2) releasing the fins so that they may be moved from their stored positions to their outwardly-extended deployed positions, and (3) thereafter controlling the angle-of-attack of these deployed fins within the air stream.
With parenthetical reference to the corresponding parts, portions or surfaces of the disclosed embodiment, merely for purposes of illustration and not by way of limitation, the present invention broadly provides an improved multi-function actuator (20), and method of operating same.
The improved actuator broadly includes: a first mechanism (21) capable of bi-directional displacement; a motor (22) operatively arranged to selectively displace the first mechanism through a first displacement range; a second mechanism (24) capable of uni-directional displacement from a first position to a second position; a spring (25) operatively arranged to urge the second mechanism to move from the first position to the second position; a release mechanism (26) operatively arranged to release the spring when the first mechanism is moved beyond the first displacement range; a third mechanism (27) capable of bi-directional displacement; and a clutch (28) operated by the release of the spring to selectively disconnect the motor from the first mechanism and to selectively connect the motor to the third mechanism; whereby the motor may be operated to sequentially control the displacement of the first mechanism, the displacement of the second mechanism, and the displacement of the third mechanism.
The first, second and third mechanisms may be arranged to operate corresponding first, second and third mechanical functions. The first mechanism may be operatively arranged to rotate a thrust vector control vane. The second mechanism may be operatively arranged to control the deployment of an aerodynamic control fin. The third mechanism may be operatively arranged to control the angle-of-attack of an aerodynamic control fin.
The first mechanism may be rotatable about a first axis (y1-y1), and may include a first crank (21). The first mechanism may be operatively arranged to control a thrust vector control vane (34). The third mechanism may includes a second crank (27). The motor may be arranged to drive the second crank through a screw (23). The clutch may be arranged to act between the first and second cranks. The second mechanism may include a cam driver (39) and wherein a mating cam surface (40) is located on the fin.
The release mechanism may include a lug (41) that is constrained to move in two orthogonal directions. More particularly, the lug may be constrained to move in one orthogonal direction (i.e., circumferentially) when the motor moves the first mechanism within the first displacement range and before the first mechanism has been moved beyond the first displacement range, and may be constrained to move in the other orthogonal direction (i.e., axially) after the first mechanism has been moved beyond the first displacement range.
The third mechanism may include a shaft 29 rotatable about a first axis. The clutch may initially couple the first and second cranks before such spring release, but may connect the third mechanism shaft to the second crank after such spring release.
The improved method broadly includes the steps of: providing a first mechanism capable of bi-directional displacement; providing a motor that is operatively arranged to selectively displace the first mechanism through a first displacement range; providing a second mechanism that is capable of uni-directional displacement from a first position to a second position; providing a spring that is operatively arranged to urge the second mechanism to move from the first position to the second position; releasing the spring when the first mechanism is moved beyond the first displacement range; providing a third mechanism that is capable of bi-directional displacement; and disconnecting the motor from the first mechanism in response to release of the spring, and connecting the motor to the third mechanism in response to release of the spring; thereby to cause the motor to sequentially control the displacement of said first mechanism, the displacement of said second mechanism, and the displacement of said third mechanism.
Accordingly, the general object of the invention is to provide an improved multi-function actuator.
Another object is to provide an improved multi-function actuator having a motor that is operatively arranged to initially control displacement of a first mechanism within a first displacement range, to allow a second mechanism to be released from a first position to a second position when the first mechanism is moved beyond the first displacement range; and to thereafter selectively disconnect the motor from the first mechanism and to selectively connect the motor to a third mechanism such that the motor may be operated to selectively control either the first mechanism or the third mechanism.
Still another object is to provide an improved method of controlling the operation of a multi-function actuator.
These and other objects and advantages will become apparent from the foregoing and ongoing written specification, the drawings and the appended claims.